Meaning of the word "close the stable door after the horse has bolted" in English

What does "close the stable door after the horse has bolted" mean in English? Explore the meaning, pronunciation, and specific usage of this word with Lingoland.

close the stable door after the horse has bolted

US /kloʊz ðə ˈsteɪbl dɔːr ˈæftər ðə hɔːrs hæz ˈboʊltɪd/
UK /kləʊz ðə ˈsteɪbl dɔːr ˈɑːftə ðə hɔːs hæz ˈbəʊltɪd/
"close the stable door after the horse has bolted" picture

Idiom

to take precautions after a misfortune has already happened

Example:
Trying to fix the security breach now is like closing the stable door after the horse has bolted.
They should have implemented stricter rules earlier, but it's too late now; they're just closing the stable door after the horse has bolted.